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Biomedical subjects

M Bureau

Publications and source records attributed to M Bureau.

At least 37 records · Page 2Linked to original sources
PubMed1995

[Myoclonus of focal action and localized hemispheric lesion. A polygraphic and pharmacological study].

Authors report a case of focal action myoclonus due to a localized hemispheric lesion. The woman had cardiac arrest complicated by ischemic stroke involving the left parietal region. Action myoclonus of the inferior right limb was the sole residual complaint, provoked by movement and maintenance of posture. Patient noted that myoclonus was worsened by carbamazepine and vigabatrin. EEG-EMG polygraphic study demonstrated action myoclonus and showed a particular EEG activity consisting in a volley of spikes on the vertex region during the right inferior limb movements. Contralateral movements did not elicit this activity. Pharmacological response to clonazepam, piracetam and alcohol was studied. A marked improvement of myoclonus was obtained with alcohol. Pathophysiology of this exceptional form of cortical action myoclonus is discussed.

Anticonvulsants↗
PubMed1994

Cerebral distribution of the B-36 VDAC protein in rat, cow and man brain: immunocytochemical study.

Polyclonal antiserum to a new voltage-dependent anion channel protein (B-36 VDAC) isolated during the purification of the GABAA receptor from bovine cerebral cortex was used to determine the localization of this protein in immunocytochemical preparations of cerebral cortex, cerebellum and hippocampal formation of rat, cow and human. The labeling was present in the Purkinje cells and some cells of the molecular layer of the rat cerebellum, as well as in pyramidal and non-pyramidal cells of the rat and human cerebral cortex; the labeling outlined the membrane surface. In the rat granule cells of the dentate gyrus and the pyramidal cells, the labelling was observed within the cells. These results indicate that the B-36 VDAC protein is heterogeneously distributed among different cerebral regions in different species and suggest that this protein would be associated with the alpha-1 subunit of the GABAA receptor (benzodiazepine binding sites).

Animals↗
PubMed1994

[Comparative biochemistry of the triune brain].

The contribution of the phylogenesis to the study of the functional organisation of brain constitutes an essential component in the integration of the current data regarding the knowledge of the central nervous system. The three evolutive structures evidenced by McLean allowed manifestation of a biological diversity particularly expressed in the neommamalian brain. Studying this biological diversity constitutes one of the field of comparative biochemistry. In this article, the authors attempt to characterize evolution through the study of GABA-receptors.

Brain Chemistry↗
PubMed1993

Vagal and chemoreceptor influences on abdominal muscle activity in awake lambs during hypoxia.

The ventilatory response to hypoxia is a complex phenomenon involving several control mechanisms. We designed this study to examine the dynamic control of abdominal muscle expiratory electromyogram (EMG) activity during room-air breathing and hypoxia and then to analyze the relative contribution of the chemoreceptors and vagal afferents. We studied 12 11- to 22-day-old awake nonsedated lambs, six intact and six vagotomized. To assess the dynamic influence of peripheral chemoreceptors on abdominal muscle expiratory activity, we performed transient testing of peripheral chemoreceptor function (pure O2 and N2 inhalation, KCN injection). To assess the influence of central chemoreceptor afferents, we compared results obtained during hypocapnic and isocapnic 15-min hypoxic runs (fractional concentration of inspired O2 0.08) in each lamb. We also compared results obtained in intact and vagotomized lambs so that the importance of vagal afferents could be assessed. We consistently observed abdominal muscle expiratory EMG activity in each lamb, whether intact or vagotomized, during baseline room air breathing; further recruitment was observed during hypoxia. We also consistently observed abdominal muscle expiratory recruitment during hypocapnic hypoxia in each lamb, although it was significantly less marked than during isocapnic hypoxia. Our transient testing of peripheral chemoreceptor function showed, furthermore, that peripheral chemoreceptor afferents dynamically modulate abdominal muscle expiratory activity. Thus, during hypoxia in 11- to 22-day-old awake nonsedated lambs, increased afferent information from peripheral chemoreceptors forcefully enhances abdominal muscle expiratory activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Muscles↗
PubMed1993

Epileptic negative myoclonus.

Five patients with partial epilepsy of diverse etiology insidiously developed action-activated jerks. The disorder was limited to one arm in two patients and to the legs in another, and was multifocal in the remaining two. Each jerk was related to an EMG silent period lasting 100 to 400 msec, causing a lapse followed by resumption of posture. Simultaneous EEG-EMG recording showed each postural lapse to be time-locked with a sharp or spike and slow-wave transient over the contralateral sensorimotor cortex, where almost continuous paroxysmal activity occurred. The three patients who were able to cooperate during neurologic evaluation also exhibited motor neglect in the most affected body segment and decreased awareness of the disorder. In three patients, the phenomenon was medically resistant, and in two of them it was continuous and could be defined as epilepsia partialis continua. In the other two, medical treatment induced remission of EEG, motor, and neuropsychological abnormalities. This disabling movement disorder can be classified as "epileptic negative myoclonus" and may result from focal-discharge-related transient disruption of cortical function in the sensorimotor cortex.

Adolescent↗
PubMed1992

Nature and frequency of chromosomal abnormalities in pregnancies with abnormal ultrasound findings: an analysis of 117 cases with review of the literature.

During a 7-year period, 117 fetal karyotypes were available from 131 genetic amniocenteses. These procedures were performed between 14 and 37 weeks' gestation for the following abnormal ultrasound findings: (1) intrauterine growth retardation (IUGR)--61 cases; (2) fetal malformation--71 cases; and (3) amniotic fluid volume (AFV) abnormality--60 cases. Chromosomal abnormalities were identified in 19 cases (16.2 per cent). Aneuploidy was 2.5 times as frequent in the presence of malformations than in their absence. No correlation was demonstrated between specific fetal malformations and specific chromosomal abnormalities. Aneuploidy was also twice as frequent in the presence of symmetrical IUGR than in its absence. No chromosomal abnormalities were found among eight cases of asymmetrical IUGR. Four cases of aneuploidy presented with isolated IUGR, three of these involving the X chromosome. The frequency of aneuploidy was the same with or without abnormalities of AFV (14.3 versus 16.4 per cent). No chromosomal abnormality was found associated with isolated AFV abnormalities.

Adult↗
PubMed1992

Characteristics of putrescine uptake and subsequent GABA formation in primary cultured astrocytes from normal C57BL/6J and epileptic DBA/2J mouse brain cortices.

Brain maturation and GABA metabolism are known to play a key role in epileptogenesis. The metabolism of the polyamines (putrescine, spermidine and spermine) is closely linked to the process of brain maturation. Putrescine has been shown to be catabolized to GABA in brain tissue and astrocytes. In order to better understand the importance of glial putrescine transport and metabolism, a model of age-dependent epilepsy was used to study the kinetic properties of [14C]putrescine uptake into cultured astrocytes from normal C57/BL and audiogenic DBA/2 newborn mice, and the subsequent GABA formation. (1) Putrescine uptake exhibited non-Michaelian allosteric kinetics with positive co-operativity (Hill factor = 2), suggesting a physiological importance of putrescine uptake by astrocytes. (2) The Vmax of putrescine uptake was significantly higher in C57/BL astrocytes than in DBA/2J, but the uptake affinity for putrescine was higher in DBA/2J than in C57/BL. (3) Higher K+ concentrations (18 mM) had little effect on putrescine uptake in either strain. (4) Ten-micromolar N-acetylputrescine, the first putrescine metabolite, stimulated putrescine uptake into astrocytes of both strains, but to a different degree: +46% in C57/BL and + 102% in DBA/2J. (5) The specific radioactivity of the GABA formed from labelled putrescine was four times higher in astrocytes from DBA/2J than from C57/BL mice. (6) The molar ratio of glutamate/GABA in the cerebral cortex of the DBA/2J mice was significantly higher during the period of audiogenic seizure susceptibility than in age-matched C57/BL mice. Our results show characteristics of putrescine uptake into astrocytes; we demonstrated distinct kinetic properties between normal and epileptic strains of mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Neurological findings and seizure outcome in children with bilateral opercular macrogyric-like changes detected by MRI.

The authors studied 10 patients aged between six and 23 years (mean age 14 years 5 months) with magnetic resonance imaging, which detected bilateral 'macrogyric-like' maldevelopment of the insulo-opercular regions. The data confirm that biopercular gyral anomaly, associated with mental retardation, pseudobulbar palsy (cortical or central) and epilepsy, represents an anatomo-clinical syndrome. Nevertheless, a wide clinical spectrum was found varying from pictures correlating with the topography and extent of the MRI-detected anomaly to conditions indicating wider cerebral involvement. Epilepsy, varying greatly in age at onset and severity, consistently influenced the prognosis for five patients with diffuse EEG abnormalities and intractable seizures with falls. Anterior callosotomy relieved such seizures in one case.

Adolescent↗
PubMed1992

Epilepsy and focal gyral anomalies detected by MRI: electroclinico-morphological correlations and follow-up.

The authors studied 10 patients (mean age 15 years 6 months) with localized developmental gyral disorder detected by MRI. There were two groups of major malformations. Seven patients (group 1) had unilateral 'macrogyric-like' insulo-opercular changes, one of whom died early in life and had extensive microgyria. The six others had mental retardation and epilepsy, three of whom had focal neurological signs. Age at onset of epilepsy varied greatly. Clinical and EEG data suggested a wider cerebral involvement than recognized on MRI. The remaining three patients (group 2) had abnormal gyri of variable topography and extension, with bulging grey matter and ventricular deformity. One had mental retardation, another had neurological signs. All had intractable complex partial seizures and focal EEG anomalies correlating with the MRI lesion site, pointing to a well-defined epileptogenic zone. No clinical or EEG evidence of significant malformation in the remaining brain tissue was observed. Ablative surgery was beneficial for one patient; focal cortical dysplasia was the pathological substrate.

Adolescent↗
PubMed1992

Effects of phenobarbital on cerebral blood flow in the newborn piglet.

To determine the neonatal cerebrovascular effect of a therapeutic dose and a high dose of phenobarbital (Pb), the effect of Pb on cerebral blood flow (CBF) and total brain oxygen consumption (CMRO2) was studied in three groups of awake newborn piglets (aged 1-3.5 days). Group I (control n = 9) received normal saline solution, group II (n = 9) received a therapeutic dose of Pb (15 mg/kg i.v.) and group III (n = 9) received a high Pb dose (45 mg/kg i.v.). Four CBF measurements per piglet using radioactive microspheres (141Ce, 85Cr, 95Nb, 46Sc), arterial blood gases, O2 content, hematocrit and plasma glucose were obtained at 0, 15, 30, 60 min after saline or Pb injections. In all groups, pH, PaO2, PaCO2, blood pressure, heart rate, temperature and plasma glucose remained unchanged except a 14% decrease (p < 0.01) in blood pressure and an increase (p < 0.05) in PaCO2, 60 min after drug injection in groups II and III. Total CBF in group II decreased by 14% (p < 0.05) 15 min after drug injection and was significantly lower (p < 0.05) than control (group I) but returned to baseline after 30 min. High Pb dose progressively lowered CBF by 11% 15 min after drug injection and produced a significant decrease by 20% (p < 0.01) 30 min after drug injection with return to baseline after 60 min. Similar effects were noted in different brain regions (cerebrum and thalamus). CMRO2 remained unchanged in the control group; however, it was decreased by 35% (< 0.01 p > 0.05) 15 min after drug injection and returned to baseline after 60 min. In group III, high Pb dose lowered CMRO2 by 31% 30 min (p = 0.02) after drug injection. Data indicate that Pb exerts a minimal but transient dose-dependent effect on CBF and CMRO2.

Animals↗
PubMed1992

The electrical status epilepticus syndrome.

The authors review the clinical and electroencephalographic features of electrical status epilepticus during slow sleep (ESES) in children. The major points of debate regard the nosology and diagnosis of ESES. The relationship between ESES and the neuropsychological impairment is emphasized. It is concluded that ESES is a separate electro-clinical entity which deserves individual categorization.

Cerebral Cortex↗
PubMed1992

Benign myoclonic epilepsy of infancy: electroclinical symptomatology and differential diagnosis from the other types of generalized epilepsy of infancy.

Benign myoclonic epilepsy in infancy (BME) is characterized by the occurrence of brief myoclonic attacks in normal infants aged 4 months to 3 years. There is no prior personal history, although in some patients 1 or 2 isolated febrile convulsions may occur prior to the onset of myoclonias. A family history of epilepsy or febrile convulsions is present in 30% of cases. Myoclonic attacks are short and mild, they involve mainly the head and upper limbs. The psychomotor development continues normally after the onset of seizures. The EEG shows a normal background activity and generalized spike-wave or polyspike-wave discharges associated with the myoclonias. These abnormalities are activated by drowsiness and during the first stages of sleep. A clinical and EEG photosensitivity is present in one-third of the patients. Myoclonias can be easily controlled by valproate monotherapy. Rare grand mal seizures can occur during adolescence, after withdrawal of drug treatment. The psychomotor evolution is good if treatment is started early. When myoclonias begin during the first year of life, the diagnoses of cryptogenic infantile spasms and of non-epileptic benign infantile myoclonus must be eliminated. In cases with a later onset, the following diagnoses can usually be easily discarded: cryptogenic Lennox-Gastaut syndrome, myoclonic-astatic epilepsy and unclassified epilepsies with the association of myoclonias and other types of seizures.

Cerebral Cortex↗
PubMed1991

Dissociation between LPS-induced bronchial hyperreactivity and airway edema in the guinea-pig.

The interactions between LPS-induced bronchial hyper-reactivity (BHR) and lung inflammation (LI) were investigated. LPS-induced LI was assessed with the augmented alveolo-capillary permeability (ACP) and with the increased migration of neutrophils into the broncho-alveolar lavage fluid. BHR was defined as the increase in the response to a standard dose of serotonin. Mepyramine and the PAF antagonist WEB 2170 blocked LPS-induced increase of ACP, whereas aspirin was inactive. By contrast, neither LPS-induced neutrophil attraction to airways, nor LPS-induced HBR were inhibited by these agents. Our results indicate that LPS-induced edema and BHR are dissociated.

Animals↗
PubMed1991

Multiple defects of the mitochondrial respiratory chain in a mitochondrial encephalopathy (MERRF): a clinical, biochemical and molecular study.

We describe a young man with a progressive neurological disorder including myoclonus, mental retardation, muscle weakness and a mitochondrial myopathy (myoclonus epilepsy and ragged red fibres--MERRF). Multiple abnormalities of the mitochondrial respiratory chain in skeletal muscle are shown by direct measurement of the flux through the individual complexes, low-temperature redox spectroscopy and decreased immunodetectable subunits of complexes I and IV by immunoblotting. No abnormality of mitochondrial DNA was found. This is the first report of combined defects of complexes I, III and IV as a cause of this clinical syndrome. However, we propose that the occurrence of multiple respiratory chain defects may be more common than previously recognised and that this particular combination of defects, involving complexes I, III and IV, may be the predominant biochemical abnormality in MERRF.

Adult↗